This MERIT extension application requests funding for Years 16-20 to continue study ofthe onset, course, causes, and consequences of alcohol use and alcohol use disorders in the Pittsburgh ADHD Longitudinal Study (PALS). In the PALS, 364 children with ADHD (probands) were ascertained in their elementary school-aged years following their participation in the ADHD Summer Treatment Program atWPIC, University of Pittsburgh. This is the largest study of its kind: rigorously diagnosed ADHD in childhood, comprehensive childhood data (including standardized and objective data), and detailed longitudinal assessments to adulthood of domains theoretically related to the development of alcohol outcomes (e.g., alcohol expectancies; family history of alcoholism). A nonADHD demographically similar group of participants (n=240) was recruited during grant Years 1-5 when probands were first followed up between the ages of 11 and 25. Using a cohort-sequential design, ADHD and nonADHD participants were interviewed annually with a high rate of retention to age 23 and at ages 25, 27, and 30; a multiple reporter approach has been adopted throughout. A sampling of findings includes: 1) a higher risk for heavy drinking and AUD by proband adolescents; 2) stronger prediction to late adolescent drinking for probands when parental knowledge is below sample median; 3) mediating role of academic performance, social impairment, delinquency, and ADHD symptom persistence; 4) stronger relation between adolescent and young adult drinking for ADHD vs. nonADHD; 5) potential contribution of alcohol use to ADHD-related elevated risky driving behavior and intimate partner violence in early adulthood; and 6) continued need for collateral report of behavior (specifically, ADHD symptoms) into adulthood. Continuation of interviews is proposed, for most participants through the late 20s and early 30s, to determine whether early heavy drinking patterns persist, whether new cases of AUD develop, to examine all alcohol outcomes in relation to differential achievement of adult milestones (employment, marriage, parenthood), and to study the putative causal mechanisms underlying these AUD developments and consequences in early adulthood.